Senior Full Stack Engineer – Java/React (m/f/d)

We are modernizing several of SIXT’s business-critical core systems by replacing legacy vendor solutions with in-house platforms used across the whole company. We are now transitioning from external/legacy solutions into fully owned internal systems, and you will play a key role in redefining how these systems are designed, built, and operated. If you want to help shape the next generation of these platforms and contribute to a large-scale transformation program, apply now. YOUR ROLE AT SIXT You understand business processes behind systems and translate them into scalable in-house solutions, not just code implementations You contribute to the modernization of legacy systems into internal platforms as part of a broader transformation initiative You design and develop end-to-end distributed systems across backend (Java) and frontend (React/TypeScript) You work on event-driven architectures using Kafka and cloud-native technologies (AWS-based environments) You build and evolve APIs (including gRPC-based services) and UI components within a microservices ecosystem You act as a senior contributor in a governance-oriented team that enables engineering teams through standards, architecture and technical guidance YOUR SKILLS MATTER Technical Background Strong experience with Java, Spring Boot, React, and TypeScript in complex production environments Experience Proven background in designing and building cloud-native, distributed systems on AWS or similar cloud providers Domain Knowledge Deep understanding of microservices architecture, ideally with hexagonal or clean architecture principles Tools & Platforms Solid experience with event-driven systems and messaging technologies such as Kafka or RabbitMQ Practices Hands-on experience with modern engineering workflows and agentic tools such as Claude Code or Cursor, used intentionally to improve delivery quality and speed Background Experience in legacy system modernization, data migration, or transformation programs in enterp